Process of preparing concentrated sulphite cellulose extract containing magnesium compounds



Patented July 13, 1926. i

UNITED STATES PATENT OFFICE.

WEBSTER E. BYRON BAKER, OF YORK HAVEN, PENNSYLVANIA- PROGESS OI PREPARING GONCENTRATEQ SULPHITE GELLULOSE EXTRACT CONTAINING MAGNESIUM COMPOUNDS.

H Drawing. Application flied March 16, 1923. Serial No. 625,620.

There is a demand for an extract containalso be added at this stage a small quantity ing magnesium compounds, and it is alleged or amount of barium or strontium hydroxide to be superior for use in making roads and solution and this can well be done in the for certain other industrial purposes and last part of the neutralization procedure and uses. However, the manufacture of such it is done for the purpose of precipitatin 0 material presents practical difliculties which as completely as possib e any sulphuric aci will be hereinafter referred to and it is the ions present as'sulphates and also for the objei i 'if the present invention to overcome purpose of removing the small amount of the those difiiculties and to provide an economsulphurous acid ions still present as sparing- 10 ical and commercially practical recess for ly soluble calcium sulphite. This last pro- 65 the manufacture of that materia cedure is appropriate when it is desirable The addition of calcined magnesia or magto remove the ions referred to as completely nesium hydroxide or oxide to the light as possible from the product and when it is liquors (sulphite waste liquor) prior to conessential that scaling be reduced as much as 1 centration, that is at the neutralization possible. If the purity of the product may 10 stage, leads into some difiiculties due to the be disregarded it is ossible to commercialfact that by that procedure a relatively large 1y operate without t e addition of barium amount of ma esium monosulphite reor strontium or both. From a scientific mains dissolved in the li nor on account of point of view it is possible and slightly adthe relatively high solu ility (1.25%) of vantageous to add only barium or strontium 7 magnesium sulphite in water. When such hydroxide to the light liquor, but manifestliquor is subjected to concentration and the 1y that is more expensive than where some heating associated therewith the magnesium milk of lime is employed. monosulphite enters into a double decom- The continuation of the process consists osition reaction with the calcium present in the filtration and concentration of the 0 in the liquor (as soluble lignosul honate) light liquor until the resultin liquor conwhich results in the formation an depos'itains about fifty per cent 0 dr matter tion of the much less soluble calcium monoand has a density of a proximate y desulphite (0.125%) as scale on the tubes and grees Baum or therea out, although I do heating surfaces of the evaporation apparanot limit this operation to any particular 85 tus, resulting in a great diminution of the resultant concentration. The filtration and rate of heat transfer. Therefore, the addiconcentration of the light liquor may well tion of ma esia as a neutralizer is im racbe efiected as described in my application ticable and actual operatin trials ave Serial No. 539,284, that is to say, by subshown that even a rapid ascen ing film type {gating it to sedimentation in any of the an of evaporator cannot be operated on such own sedimentation or thickening apparaliquor for a period of more than twentytus or simply in a tank for a suilicient time fourtoforty-eight hours without the deposito settle t e ma1or portion of the larger tion of a very troublesome amount of scale. particles. The supernatant liquor is drawn 40 Furthermore, the resulting product will conoff and plassed through a filter capable of as tain a relatively large amount of sulphur holding t e finest precipitates. While I do dioxide as sul bits which is injurious to the not limit this procedure to any particular functioning 0 the concentrated extract as a. form of filtration apparatus it will be found road binder and which also exerts a decomdesirable in most cases to use a high speed posing influence on the organic constituents centrifugal of the unperforated basket or of the liquor while in process of concentrabowl type, which discharges the clear liqu d tion in the evaporator, causing a greater from the basket or bowl withoi it passing it amount of reversion to acidic condition, and through the cake, which is preci itated in a producing a higher amount of acidity in the compact mass on the side of t e bowl or condensation waters imparting to them a basket while the filtrate flows over the top hi hly corrosive action. of the basket or bowl or out at the bottom.

the present invention these difliculties The resulting clear liquor is concentrated to are overcome by adding milk of lime to the about fifty per cent solids content without light liquor until the hydrogen ion concendeoom osition. Decomposition is prevented tration of the liquor is PHI-9. There may by avoiding and minimizing the exposure of the liquid to high temperature, particularly as the concentration progresses. While any type of apparatus, or method of obtaining these conditions may be employed it will found most advantageous and most economical to do this in a multiple efl'ect vacuum evaporator, and of these the rapid film type is most desirable. The evaporator may be constructed of cast iron, with narrow steel tubes. No appreciable increment in iron content will be experienced if the ra id film ty e is used l Vhile in al cases not essential, good results are attained by collecting the liquors rior to neutralization and while still nearly oiling hot and filtering out fibers and solid materials in suspension and then pumping them while still hot through a fine spray nozzle or nozzles into the air under sufficient pressure to produce a mist. When this is done gaseous impurities or components are volatilized and organic compounds are oxidized.

In accordance with the present invention and in order to replace the lime (calcium and other metals, barium and strontium, if present) by magnesium the concentrated liquid extract is treated with the necessary quantity of a concentrated solution of magnesium sulphate. A double decomposition takes place and the magnesium goes into the extract and the calcium (and barium and strontium if present) is separated from the extract as calcium sulphate (barium and strontium as corresponding sulphates) in finely divided form, whereupon the extract is filtered by the use of any type of filtration apparatus and is then ready for use, for example, for making roads as has been stated. The finely divided sulphate precipitate may be washed and dried and is valuable for various uses among which reference may be made to paper manufacture.

While all the ime present in the extract may thus be removed, or at least very nearly all, it is obvious that if desired for any particular use only a portion of the lime may be removed or exchanged for magnesium.

Sulphite cellulose waste liquor or, as it is often called, light liquor is what the process starts with, and it is acid. The extract is what the process makes and it is neutral or slightly basic and contains magnesium compounds.

It will be obvious to those skilled in the art that modifications may be made in details of procedure without departing from the spirit of the invention which, being of a chemical nature, is entitled to the range of equivalents appropriate to that class of inventio'ns and whic is not limited otherwise than as the appended claims and theprior art may require.

I claim:

1. The process of preparing concentrated sulphite cellulose extract containing substantially all or a given part, of its basic constituents in the form of magnesia which consists in neutralizing low density sulphite waste liquor with a compound of an alkaline earth metal which forms insoluble sulphates and sulphites and concentrating it treating the resulting concentrated liqui extract with a resulting concentrated solution of magnesium sulphate thereby effecting a double decomposition in which the magnesium goes into the concentrated liquid and the basic constituent of the concentrated liquid separates as sulphate in finely divided form, and separating the latter from the finished concentrated extract, substantially as described. i

2. The process of preparing concentrated sulphite cellulose extract containin substantially all or a given part of its basic constituents in the form of magnesia which consists in neutralizing waste liquor at substantially the density at which it is discharged from the digestor with alkaline earth metal oxide or hydroxide until the hydrogen ion concentration of the liquor is pH9, filtering the basic liquor and concentrating it to make a concentrated solution having its basic constituent other than magnesium and containing comparatively little sulphur dioxide as sulphite, treating the concentrated solution with a concentrated solution of magnesium sulphate thereby effecting a double decompositon in which the magnesium goes into the solution and the basic constituent of the solution precipitates as sulphate in finely divided form, and separating the latter from the finished concen trated extract, substantially as described.

3. The process of preparing concentrated sulphite cellulose extract containing substantially all or a given part of its basic constituents in the form of magnesia which consists in neutralizing low densit sulphite waste liquor with calcium oxi e or hydroxide and concentrating it to make a concentrated solution, treating the concentrated solution with a concentrated solution of magnesium sulphate thereby effecting a double decomposition in which magnesium goes into the solution and sulphate of calcium in finely divided form precipitates, and separating the sulphate of calcium from the finished extract, substantially as described.

4. The process of preparing concentrated sulphite cellulose extract containin substantially all or a given part of its asic constituents in the form of magnesia which consists in neutralizin low density sulphite waste liquor with oxi e or hydroxide of alkaline earth metals excluding magnesium and includin alkaline form insolubfii sulphates and concentrating it to make a concentrated solution containmg comparatively little sulphur dioxide as earth metals which sulphite, treating the concentrated solution with a concentrated solution of magnesium sulphate thereby effecting a double decomposition in which the magnesium goes into the solution and the basic constituents precipitate as sulphates in finely divided form, and separating the latter from the finished extract, substantially as described.

5. In the process of preparing concentrated sulphite cellulose extract containing substantially all or a given part of its basic constituents in the form of magnesia the improved step Which consists in treating the low density sulphite Waste liquor after neutralization with a compound of an alkaline earth metal which forms insoluble Sulphate and for the first time with a magnesium compound, adapted to produce a double decomposition in which the magnesium goes into the finished extract, substantially as described.

WEBSTER E. BYRON BAKER.

constituents in the form of magnesia the improved step which consists in treating the low density sulphite waste liquor after neutralization with a compound of an alkaline earth metal which forms insoluble sulphate and for the first time with a magnesium compound, adapted to produce a double decomposition in which the magnesium goes into the finished extract, substantially as descr ibed.

\VEBSTER E. BYRON BAKER.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,592,063, upon the application of Webster E. Byron Baker, of York ranted July 13, 1926, aven, Pennsylvania,

for an improrernent in Processes of Preparing Concentrated Sulphite ellulose Extract Conta ning Magnesium Compounds, an error appears in the printed specificat1on re uiring correction as follows: Page 2, line 74, claim 1, strike out the Word resulting and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 7th day of December, A. D. 1926.

[emu] M. J. MOORE, Acting Comicsioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,592,063, antecl July 13, 1926, upon the application of Webster E. Byron Baker, of York aven, Pennsylvania, for an improvement in Processes of Preparing Concentrated Sulphite Cellulose Extract Containing Magnesium Compounds, an error appears in the printed specification requiring correction as follows: Page 52. line 74, claim 1, strike out the word resulting and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of December, A. D. 1926.

M. J. MOORE,

Acting Commissioner of Patents. 

